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Properties of a Proper-Motion Selected Sample of Giants in the Small Magellanic Cloud near NGC 121

Nicholas B. Suntzeff·Alistair R. Walker·Verne V. Smith·Robert P. Kraft·Arnold Klemola·Peter B. Stetson
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Abstract

We present both low and high-dispersion abundance analyses of giants drawn from the zero proper motion sample near NGC 121. For the sample of 35 stars, the mean metallicity of the SMC field near NGC 121 is [Fe/H]=-1.3 with a real dispersion of 0.4 dex. The most metal-rich stars are at -0.5 dex and the most metal-poor stars at -2.1 dex. The velocity dispersion of the sample is 25 km/s. The dispersion of various kinematic samples in the SMC is independent of age. The RGB colors are consistent with Galactic globular clusters of similar metallicity. The field population, however, does not have an extended blue horizontal branch, and the main sequence turnoff extends 1 magnitude brighter than the turnoff in M5. Evidently active star formation in this region started roughly at the age of the Galactic globular cluster M5 and extended for about 6 Gyrs, and then stopped.

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Nicholas B. Suntzeff, Alistair R. Walker, Verne V. Smith, Robert P. Kraft, Arnold Klemola, Peter B. Stetson. 1998-09-28. Properties of a Proper-Motion Selected Sample of Giants in the Small Magellanic Cloud near NGC 121. https://arxiv.org/abs/astro-ph/9809358

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